Remove code to defer app window appearance until first paint.

extensions/renderer/resources/app_window_custom_bindings.js

Index: extensions/renderer/resources/app_window_custom_bindings.js
diff --git a/extensions/renderer/resources/app_window_custom_bindings.js b/extensions/renderer/resources/app_window_custom_bindings.js
index 546183f8428a3a87eeb050c109037960c7961228..376e3671bd583319a747dbf9e2969b354d10be7a 100644
--- a/extensions/renderer/resources/app_window_custom_bindings.js
+++ b/extensions/renderer/resources/app_window_custom_bindings.js
@@ -222,7 +222,6 @@ appWindow.registerCustomHook(function(bindingsAPI) {
     AppWindow.prototype.resizeTo = $Function.bind(window.resizeTo, window);
     AppWindow.prototype.contentWindow = window;
     AppWindow.prototype.onClosed = new Event();
-    AppWindow.prototype.onWindowFirstShownForTests = new Event();
     AppWindow.prototype.close = function() {
       this.contentWindow.close();
     };
@@ -253,15 +252,6 @@ appWindow.registerCustomHook(function(bindingsAPI) {
     AppWindow.prototype.alphaEnabled = function() {
       return appWindowData.alphaEnabled;
     };
-    AppWindow.prototype.handleWindowFirstShownForTests = function(callback) {
-      // This allows test apps to get have their callback run even if they
-      // call this after the first show has happened.
-      if (this.firstShowHasHappened) {
-        callback();
-        return;
-      }
-      this.onWindowFirstShownForTests.addListener(callback);
-    }
 
     Object.defineProperty(AppWindow.prototype, 'id', {get: function() {
       return appWindowData.id;
@@ -366,16 +356,6 @@ function updateAppWindowProperties(update) {
     dispatchEventIfExists(currentWindow, "onAlphaEnabledChanged");
 };
 
-function onAppWindowShownForTests() {
-  if (!currentAppWindow)
-    return;
-
-  if (!currentAppWindow.firstShowHasHappened)
-    dispatchEventIfExists(currentAppWindow, "onWindowFirstShownForTests");
-
-  currentAppWindow.firstShowHasHappened = true;
-}
-
 function onAppWindowClosed() {
   if (!currentAppWindow)
     return;
@@ -407,4 +387,3 @@ function updateSizeConstraints(boundsType, constraints) {
 exports.$set('binding', appWindow.generate());
 exports.$set('onAppWindowClosed', onAppWindowClosed);
 exports.$set('updateAppWindowProperties', updateAppWindowProperties);
-exports.$set('appWindowShownForTests', onAppWindowShownForTests);